The present invention relates to an information-processing apparatus, an information-processing method and a recording medium. More particularly, the present invention relates to an information-processing apparatus, an information-processing method and a recording medium of a transcoding system that allow information to be transmitted in such a way that necessary information can be extracted from the transmitted information with ease in dependence on the degree of information importance, and allow information to be read out from the information-recording medium wherein the picture quality does not deteriorate even if decoding and encoding processes are carried out repeatedly to modify the structure of an encoded bit stream completing an encoding process based on an MPEG (Moving Picture Expert Group) standard.
In recent years, in a broadcasting station for producing and broadcasting television programs, an MPEG technology is generally adopted to carry out processing to compress and/or encode video data. In particular, the MPEG technology is becoming a de-facto standard for recording video data into a random-access recording medium material or a tape and transmitting video data through a cable or by way of a satellite.
The following description briefly explains typical processing carried out at a broadcasting station up to transmission of a video program produced at the broadcasting station to homes. First of all, an encoder employed in a cam-coder encodes source video data and records the encoded data onto a magnetic tape of a VTR (Video Tape Recorder). A cam-coder is an apparatus comprising a video camera and the VTR, which are integrated to form a single body. At that time, the encoder employed in the cam-coder encodes the source video data into codes with a recording format suitable for the magnetic tape of the VTR. For example, in a GOP (Group of Pictures) structure of an MPEG bit stream recorded onto the magnetic tape, 1 GOP consists of 2 picture frames. Thus, an MPEG bit stream is a sequence of picture frames such as I, B, I, B, I, B and so on where notations I and B represent picture frames with different types. An MPEG bit stream is recorded onto a magnetic tape at a bit rate of 18 Mbps.
Then, edit processing is carried out at a main broadcasting station to edit the video bit stream recorded on the magnetic tape. In order to carry out the edit processing, the GOP structure of the video bit stream recorded on the magnetic tape is converted into a GOP structure suitable for the edit processing. In a GOP structure suitable for the edit processing, 1 GOP comprises 1 frame and all pictures are I pictures. This is because, in order to carry out the edit processing in frame units, the I picture is most suitable since the I picture has no correlation with other pictures. In an actual edit operation, the video bit stream recorded on the magnetic tape is first decoded, being restored to base-band video data. Then, the base-band video signal is re-encoded so as to convert each picture into an I picture. By carrying out decoding and re-encoding processes in this way, it is possible to generate a bit stream having a GOP structure suitable for the edit processing.
Next, in order to transmit an edited video program obtained as a result of the editing described above from the main broadcasting station to a local broadcasting station, the GOP structure and the bit rate of the bit stream of the edited video program are converted into a GOP structure and a bit rate that are suitable for transmission processing. A GOP structure suitable for transmission between stations is a GOP structure in which 1 GOP consists of 15 picture frames such as I, B, B, P, B, B, P: and so on where notation P represents a picture frame of a certain type different from the picture frames I and B. On the other hand, a desirable value of the bit rate suitable for transmission between stations is at least 50 Mbps. This is because a dedicated transmission line having a high transmission capacity is generally used for transmission between stations. To put it concretely, the bit stream of the video program obtained as a result of the edit processing is first decoded, being restored to base-band video data. Then, the base-band video data is re-encoded to convert the GOP structure and the bit rate of the base-band video data into a GOP structure and a bit rate that are suitable for the transmission processing.
At a local broadcasting station, edit processing is carried out to insert commercials unique to the geographical area of the local broadcasting station into the video program received from the main broadcasting station. That is to say, much like the edit processing described above, the video bit stream received from the main broadcasting station is first decoded, being restored to base-band video data. Then, the base-band video signal is re-encoded so as to convert each picture into an I picture. By carrying out decoding and encoding processes in this way, it is possible to generate a bit stream having a GOP structure suitable for the edit processing.
Next, in order to transmit an edited video program obtained as a result of the editing described above from the local broadcasting station to homes, the GOP structure and the bit rate of the bit stream of the edited video program are converted into a GOP structure and a: bit rate that are suitable for transmission processing. A GOP structure suitable for transmission from a local broadcasting station to homes is a GOP structure in which 1 GOP consists of 15 picture frames such as I, B, B, P, B, B, P and so on. On the other hand, a desirable value of the bit rate suitable for transmission from a local broadcasting station to homes is about 5 Mbps. To put it concretely, the bit stream of the video program obtained as a result of the edit processing is first decoded, being restored to base-band video data. Then, the base-band video data is re-encoded to convert the GOP structure and the bit rate of the base-band video data into a GOP structure and a bit rate that are suitable for the transmission processing.
As is obvious from the above description, during transmission of a video program from the main broadcasting station to homes, decoding and encoding processes are carried out repeatedly a plurality of times. In actuality, processing carried out at a broadcasting station includes various kinds of necessary signal processing other than the signal processing described above and, for each signal processing, decoding and encoding processes must be performed.
Unfortunately, however, encoding and decoding processes based on the MPEG standard are not 100% reversible processes as is generally known. That is to say, video data obtained as a result of a decoding process is not 100% the same as base-band video data prior to an encoding process. To be more specific, the picture quality deteriorates due to the encoding and decoding processes. To put it in detail, when the encoding and decoding processes are carried out repeatedly as described above, there is raised a problem that the picture quality inevitably deteriorates each time a process is performed. In other words, each time the decoding and/or encoding processes are repeated, the picture quality deteriorates cumulatively.
In order to solve this problem, there has been proposed a technique for preventing the picture quality from deteriorating by transmission of an encoding history of transmitted video data along with the video data and execution of encoding and decoding processes by using the encoding history.
In the execution of the decoding and encoding processes, however, a transcoding system may not require all parameters in some cases in dependence on the application to process pictures. Since an area in which required data is located is not known, nevertheless, it is necessary to design such hardware that all data is accessible to the transcoding system. For this reason, the hardware becomes unavoidably complicated and, as a result, the information-processing apparatus inevitably becomes large in scale. In addition, if a packet is lost due to an effect of a noise, restoration of data including and following the lost packet becomes difficult so that it is feared that much data is unavoidably lost.
It is thus an object of the present invention addressing the problems described above to provide an information-processing apparatus, an information-processing method and a recording medium that allow information to be transmitted in such a way that necessary information can be extracted from the transmitted information with ease by modifying a technique to superpose data in dependence on the degree of data importance and by recording the data at predetermined locations such as a vertical blanking area and a horizontal blanking area, and allow information to be read out from the information-recording medium in a transcoding system wherein the picture quality does not deteriorate even if decoding and encoding processes are carried out repeatedly to modify the GOP structure of an encoded bit stream completing an encoding process based on the MPEG standard.
To achieve the above object, according to a first aspect of the present invention, there is provided an information-processing apparatus for decoding an input encoded stream and generating an output signal, the information-processing apparatus including extraction means for extracting auxiliary data from the input encoded stream, separation means for splitting the auxiliary data extracted by the extraction means into first auxiliary data and second auxiliary data, conversion means for converting the first auxiliary data and the second auxiliary data, which were separated by the separation means, into data having a predetermined format, and insertion means for inserting the first auxiliary data and the second auxiliary data, which were converted by the conversion means, into a first position and a second position of the output signal respectively.
According to a second aspect of the present invention, there is provided an information-processing method adopted by an information-processing apparatus for decoding an input encoded stream and generating an output signal, the information-processing method including an extraction step of extracting auxiliary data from the input encoded stream, a separation step of splitting the auxiliary data extracted at the extraction step into first auxiliary data and second auxiliary data, a conversion step of converting the first auxiliary data and.,the second auxiliary data, which were separated at the separation step, into data having a predetermined format, and an insertion step of inserting the first auxiliary data and the second auxiliary data, which were converted at the conversion step, into a first position and a second position of the output signal respectively.
According to a third aspect of the present invention, there is provided a recording medium employed in an information-processing apparatus for decoding an input encoded stream and generating an output signal, the recording medium used for recording a program executable by a computer to implement a method including an extraction step of extracting auxiliary data from the input encoded stream, a separation step of splitting the auxiliary data extracted at the extraction step into first auxiliary data and second auxiliary data, a conversion step of converting the first auxiliary data and the second auxiliary data, which were separated at the separation step, into data having a predetermined format, and an insertion step of inserting the first auxiliary data and the second auxiliary data, which were converted at the conversion step, into a first position and a second position of the output signal respectively.
In the information-processing apparatus, the information-processing method and the recording medium, it is possible to generate and output data from which required information can be fetched with ease on a reception side.
According to a fourth aspect of the present invention, there is provided an information-processing apparatus for encoding an input signal and generating an output signal, the information-processing apparatus including extraction means for extracting first auxiliary data or second auxiliary data, which were inserted into a first position or a second position of the input signal respectively, selection means for selecting either the first auxiliary data or the second auxiliary data, which were extracted by the extraction means, and encoding means for encoding the input signal by utilizing the first auxiliary data or the second auxiliary data, which were selected by the selection means.
According to a fifth aspect of the present invention, there is provided an information-processing method adopted in an information-processing apparatus for encoding an input signal and generating an output signal, the information-processing method including an extraction step of extracting first auxiliary data or second auxiliary data, which were inserted into a first position or a second position of the input signal respectively, a selection step of selecting either the first auxiliary data or the second auxiliary data, which were extracted at the extraction step, and an encoding step of encoding the input signal by utilizing the first auxiliary data or the second auxiliary data, which were selected at the selection step.
According to a sixth aspect of the present invention, there is provided a recording medium employed in an information-processing apparatus for encoding an input signal and generating an output signal, the recording medium used for recording a program executable by a computer to implement a method including an extraction step of extracting first auxiliary data or second auxiliary data, which were inserted into a first position or a second position of the input signal respectively, a selection step of selecting either the first auxiliary data or the second auxiliary data, which were extracted at the extraction step, and an encoding step of encoding the input signal by utilizing the first auxiliary data or the second auxiliary data, which were selected at the selection step.
In the information-processing apparatus, the information-processing method and the recording medium, it is possible to fetch only necessary information with ease from the input signal and use the information in an encoding process.
According to a seventh aspect of the present invention, there is provided an information-processing apparatus for generating a second encoded stream from a first input encoded stream and outputting the second encoded stream, the information-processing apparatus including decoding means for decoding the first input encoded stream, and generation means for encoding the first encoded stream decoded by the decoding means to generate the second encoded stream, wherein the decoding means has first extraction means for extracting auxiliary data from the first input encoded stream, separation means for splitting the auxiliary data extracted by the first extraction means into first auxiliary data and second auxiliary data, conversion means for converting the first auxiliary data and the second auxiliary data, which were separated by the separation means, into data having a predetermined format, and insertion means for inserting the first auxiliary data and the second auxiliary data, which were converted by the conversion means, respectively into a first position and a second position of the first encoded stream decoded by the decoding means, the decoding means decodes the first encoded stream by using the auxiliary data extracted by the first extraction means, the generation means has second extraction means for extracting the first auxiliary data or the second auxiliary data respectively from the first position or the second position of the first encoded stream decoded by the decoding means, and selection means for selecting either the first auxiliary data or the second auxiliary data, which were extracted by the second extraction means, and the generation means encodes the first encoded stream decoded and supplied thereto by the decoding means by using the first auxiliary data or the second auxiliary data, which was selected by the selection means, to generate the second encoded stream.
According to an eighth aspect of the present invention, there is provided an information-processing method adopted by an information-processing apparatus for generating a second encoded stream from a first input encoded stream and outputting the second encoded stream, the information-processing method including a decoding step of decoding the first input encoded stream, and a generation step of encoding the first encoded stream decoded at the decoding step to generate the second encoded stream, wherein the decoding step has a first extraction sub-step of extracting auxiliary data from the first input encoded stream, a separation sub-step of splitting the auxiliary data extracted at the first extraction sub-step into first auxiliary data and second auxiliary data, a conversion sub-step of converting the first auxiliary data and the second auxiliary data, which were separated at the separation sub-step, into data having a predetermined format, and an insertion sub-step of inserting the first auxiliary data and the second auxiliary data, which were converted at the conversion sub-step, respectively into a first position and a second position of the first encoded stream decoded at the decoding step, the decoding step is executed to decode the first encoded stream by using the auxiliary data extracted at the first extraction sub-step, the generation step has a second extraction sub-step of extracting the first auxiliary data or the second auxiliary data respectively from the first position or the second position of the first encoded stream decoded at the decoding step, and a selection sub-step of selecting either the first auxiliary data or the second auxiliary data, which was extracted at the second extraction sub-step, and the generation step is executed to encode the first encoded stream decoded and supplied thereto at the decoding step by using the first auxiliary data or the second auxiliary data, which was selected at the selection sub-step, to generate the second encoded stream.
According to a ninth aspect of the present invention, there is provided a recording medium employed in an information-processing apparatus for generating a second encoded stream from a first input encoded stream and outputting the second encoded stream, the recording medium used for recording a program executable by a computer to implement a method including a decoding step of decoding the first input encoded stream, and a generation step of encoding the first encoded stream decoded at the decoding step to generate the second encoded stream, wherein the decoding step has a first extraction sub-step of extracting auxiliary data from the first input encoded stream, a separation sub-step of splitting the auxiliary data extracted at the first extraction sub-step into first auxiliary data and second auxiliary data, a conversion sub-step of converting the first auxiliary data and the second auxiliary data, which were separated at the separation sub-step, into data having a predetermined format, and an insertion sub-step of inserting the first auxiliary data and the second auxiliary data, which were converted at the conversion sub-step, respectively into a first position and a second position of the first encoded stream decoded at the decoding step, the decoding step is executed to decode the first encoded stream by using the auxiliary data extracted at the first extraction sub-step, the generation step has a second extraction sub-step of extracting the first auxiliary data or the second auxiliary data respectively from the first position or the second position of the first encoded stream decoded at the decoding step, and a selection sub-step of selecting either the first auxiliary data or the second auxiliary data, which was extracted at the second extraction sub-step, and the generation step is executed to encode the first encoded stream decoded and supplied thereto at the decoding step by using the first auxiliary data or the second auxiliary data, which was selected at the selection sub-step, to generate the second encoded stream.
In the information-processing apparatus, the information-processing method and the recording medium, it is possible to fetch only necessary information with ease from the input signal and use the information in an encoding process.
According to a tenth aspect of the present invention, there is provided a decoding apparatus for decoding an encoded source stream, the decoding apparatus including decoding means for decoding the encoded source stream in order to generate a base-band video signal by using encoding parameters included in the encoded source stream, vertical insertion means for inserting much required ones among the encoding parameters into a vertical-blanking period of the base-band video signal, and horizontal insertion means for inserting little required ones among the encoding parameters into a horizontal-blanking period of the base-band video signal.
According to an eleventh aspect of the present invention, there is provided a decoding method adopted by a decoding apparatus for decoding an encoded source stream, the decoding method including the steps of decoding the encoded source stream in order to generate a base-band video signal by using encoding parameters included in the encoded source stream, inserting much required ones among the encoding parameters into a vertical-blanking period of the base-band video signal, and inserting little required ones among the encoding parameters into a horizontal-blanking period of the base-band video signal.
According to a twelfth aspect of the present invention, there is provided a decoding apparatus for decoding an encoded source stream, the decoding apparatus including decoding means for decoding the encoded source stream in order to generate a base-band video signal by using encoding parameters included in the encoded source stream, vertical insertion means for inserting those of picture and higher layers among the encoding parameters into a vertical-blanking period of the base-band video signal, and horizontal insertion means for inserting those of slice and lower layers among the encoding parameters into a horizontal-blanking period of the base-band video signal.
According to a thirteenth aspect of the present invention, there is provided a decoding method adopted by a decoding apparatus for decoding an encoded source stream, the decoding method including the steps of decoding the encoded source stream in order to generate a base-band video signal by using encoding parameters included in the encoded source stream, inserting those of picture and higher layers among the encoding parameters into a vertical-blanking period of the base-band video signal, and inserting those of slice and lower layers among the encoding parameters into a horizontal-blanking period of the base-band video signal.
According to a fourteenth aspect of the present invention, there is a decoding apparatus for decoding an encoded source stream, the decoding apparatus including decoding means for decoding the encoded source stream in order to generate a base-band video signal by using encoding parameters included in the encoded source stream, vertical insertion means for inserting general ones among the encoding parameters into a vertical-blanking period of the base-band video signal, and horizontal insertion means for inserting detailed ones among the encoding parameters into a horizontal-blanking period of the base-band video signal.
According to a fifteenth aspect of the present invention, there is provided a decoding method adopted by a decoding apparatus for decoding an encoded source stream, the decoding method including the steps of decoding the encoded source stream in order to generate a base-band video signal by using encoding parameters included in the encoded source stream, inserting general ones among the encoding parameters into a vertical-blanking period of the base-band video signal, and inserting detailed ones among the encoding parameters into a horizontal-blanking period of the base-band video signal.
According to a sixteenth aspect of the present invention, there is provided an encoding apparatus for encoding a base-band video signal, the encoding apparatus including extraction means for extracting much required encoding parameters from a vertical blanking period of the base-band video signal and little required encoding parameters from a horizontal blanking period of the base-band video signal, and re-encoding means for re-encoding the base-band video signal by referring to the much required encoding parameters and the little required encoding parameters.
According to a seventeenth aspect of the present invention, there is provided an encoding method adopted in an encoding apparatus for encoding a base-band video signal, the encoding method including the steps of extracting much required encoding parameters from a vertical blanking period of the base-band video signal and little required encoding parameters from a horizontal blanking period of the base-band video signal, and re-encoding the base-band video signal by referring to the much required encoding parameters and the little required encoding parameters.
According to an eighteenth aspect of the present invention, there is provided an encoding apparatus for encoding a base-band video signal, the encoding apparatus including extraction means for extracting encoding parameters of picture and higher layers from a vertical blanking period of the base-band video signal and encoding parameters of slice and lower layers from a horizontal blanking period of the base-band video signal, and re-encoding means for re-encoding the base-band video signal by referring to the encoding parameters of picture and higher layers and the encoding parameters of slice and lower layers.
According to a nineteenth aspect of the present invention, there is provided an encoding method adopted in an encoding apparatus for encoding a base-band video signal, the encoding method including the steps of extracting encoding parameters of picture and higher layers from a vertical blanking period of the base-band video signal and encoding parameters of slice and lower layers from a horizontal blanking period of the base-band video signal, and re-encoding the base-band video signal by referring to the encoding parameters of picture and higher layers and the encoding parameters of slice and lower layers.
According to a twentieth aspect of the present invention, there is provided an encoding apparatus for encoding a base-band video signal, the encoding apparatus including extraction means for extracting general encoding parameters from a vertical blanking period of the base-band video signal and detailed encoding parameters from a horizontal blanking period of the base-band video signal, and re-encoding means for re-encoding the base-band video signal by referring to the general encoding parameters and the detailed encoding parameters.
According to a twenty-first aspect of the present invention, there is provided an encoding method adopted in an encoding apparatus for encoding a base-band video signal, the encoding method including the steps of extracting general encoding parameters from a vertical blanking period of the base-band video signal and detailed encoding parameters from a horizontal blanking period of the base-band video signal, and re-encoding the base-band video signal by referring to the general encoding parameters and the detailed encoding parameters.
The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, take in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.